<?php
/**
 * Zend Framework
 *
 * LICENSE
 *
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@zend.com so we can send you a copy immediately.
 *
 * @category   Zend
 * @package    Zend_Search_Lucene
 * @subpackage Search
 * @copyright  Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 * @version    $Id: Term.php 18954 2009-11-12 20:01:33Z alexander $
 */


/** Zend_Search_Lucene_Search_Query */
require_once 'Zend/Search/Lucene/Search/Query.php';


/**
 * @category   Zend
 * @package    Zend_Search_Lucene
 * @subpackage Search
 * @copyright  Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 */
class Zend_Search_Lucene_Search_Query_Term extends Zend_Search_Lucene_Search_Query
{
	/**
	 * Term to find.
	 *
	 * @var Zend_Search_Lucene_Index_Term
	 */
	private $_term;

	/**
	 * Documents vector.
	 *
	 * @var array
	 */
	private $_docVector = null;

	/**
	 * Term freqs vector.
	 * array(docId => freq, ...)
	 *
	 * @var array
	 */
	private $_termFreqs;


	/**
	 * Zend_Search_Lucene_Search_Query_Term constructor
	 *
	 * @param Zend_Search_Lucene_Index_Term $term
	 * @param boolean $sign
	 */
	public function __construct(Zend_Search_Lucene_Index_Term $term)
	{
		$this->_term = $term;
	}

	/**
	 * Re-write query into primitive queries in the context of specified index
	 *
	 * @param Zend_Search_Lucene_Interface $index
	 * @return Zend_Search_Lucene_Search_Query
	 */
	public function rewrite(Zend_Search_Lucene_Interface $index)
	{
		if ($this->_term->field != null) {
			return $this;
		} else {
			require_once 'Zend/Search/Lucene/Search/Query/MultiTerm.php';
			$query = new Zend_Search_Lucene_Search_Query_MultiTerm();
			$query->setBoost($this->getBoost());

			require_once 'Zend/Search/Lucene/Index/Term.php';
			foreach ($index->getFieldNames(true) as $fieldName) {
				$term = new Zend_Search_Lucene_Index_Term($this->_term->text, $fieldName);

				$query->addTerm($term);
			}

			return $query->rewrite($index);
		}
	}

	/**
	 * Optimize query in the context of specified index
	 *
	 * @param Zend_Search_Lucene_Interface $index
	 * @return Zend_Search_Lucene_Search_Query
	 */
	public function optimize(Zend_Search_Lucene_Interface $index)
	{
		// Check, that index contains specified term
		if (!$index->hasTerm($this->_term)) {
			require_once 'Zend/Search/Lucene/Search/Query/Empty.php';
			return new Zend_Search_Lucene_Search_Query_Empty();
		}

		return $this;
	}


	/**
	 * Constructs an appropriate Weight implementation for this query.
	 *
	 * @param Zend_Search_Lucene_Interface $reader
	 * @return Zend_Search_Lucene_Search_Weight
	 */
	public function createWeight(Zend_Search_Lucene_Interface $reader)
	{
		require_once 'Zend/Search/Lucene/Search/Weight/Term.php';
		$this->_weight = new Zend_Search_Lucene_Search_Weight_Term($this->_term, $this, $reader);
		return $this->_weight;
	}

	/**
	 * Execute query in context of index reader
	 * It also initializes necessary internal structures
	 *
	 * @param Zend_Search_Lucene_Interface $reader
	 * @param Zend_Search_Lucene_Index_DocsFilter|null $docsFilter
	 */
	public function execute(Zend_Search_Lucene_Interface $reader, $docsFilter = null)
	{
		$this->_docVector = array_flip($reader->termDocs($this->_term, $docsFilter));
		$this->_termFreqs = $reader->termFreqs($this->_term, $docsFilter);

		// Initialize weight if it's not done yet
		$this->_initWeight($reader);
	}

	/**
	 * Get document ids likely matching the query
	 *
	 * It's an array with document ids as keys (performance considerations)
	 *
	 * @return array
	 */
	public function matchedDocs()
	{
		return $this->_docVector;
	}

	/**
	 * Score specified document
	 *
	 * @param integer $docId
	 * @param Zend_Search_Lucene_Interface $reader
	 * @return float
	 */
	public function score($docId, Zend_Search_Lucene_Interface $reader)
	{
		if (isset($this->_docVector[$docId])) {
			return $reader->getSimilarity()->tf($this->_termFreqs[$docId]) *
			$this->_weight->getValue() *
			$reader->norm($docId, $this->_term->field) *
			$this->getBoost();
		} else {
			return 0;
		}
	}

	/**
	 * Return query terms
	 *
	 * @return array
	 */
	public function getQueryTerms()
	{
		return array($this->_term);
	}

	/**
	 * Return query term
	 *
	 * @return Zend_Search_Lucene_Index_Term
	 */
	public function getTerm()
	{
		return $this->_term;
	}

	/**
	 * Query specific matches highlighting
	 *
	 * @param Zend_Search_Lucene_Search_Highlighter_Interface $highlighter  Highlighter object (also contains doc for highlighting)
	 */
	protected function _highlightMatches(Zend_Search_Lucene_Search_Highlighter_Interface $highlighter)
	{
		$highlighter->highlight($this->_term->text);
	}

	/**
	 * Print a query
	 *
	 * @return string
	 */
	public function __toString()
	{
		// It's used only for query visualisation, so we don't care about characters escaping
		if ($this->_term->field !== null) {
			$query = $this->_term->field . ':';
		} else {
			$query = '';
		}

		$query .= $this->_term->text;

		if ($this->getBoost() != 1) {
			$query = $query . '^' . round($this->getBoost(), 4);
		}

		return $query;
	}
}

